Overview

Hypothyroidism, also called underactive thyroid, is a medical condition where the thyroid gland fails to produce and release adequate quantities of thyroid hormones into the bloodstream. It leads to slow metabolic processes, gaining of weight and fatigue.

The thyroid gland and its location

• It is a small gland shaped as a butterfly, located in the neck anterior to the trachea.
• It produces hormones which are involved in metabolism.

 Facts & Figures

Key facts and statistics that surround hypothyroidism

• Any person can have an underactive thyroid.
• It is more common among female individuals above the age of 60, especially those that have hit menopause.

 

 Risk Factors

What are the risk factors for hypothyroidism?

• As stated earlier, any individual can have an underactive thyroid.
• There is increased chance of developing hypothyroidism if an individual:

1.  Is a woman or was assigned female at birth.
2. Has an autoimmune disease such as lupus and rheumatoid arthritis.
3. Is expectant.
4. Starts taking certain medicines and then stops.
5. Has had a previous history of neck or head radiotherapy.
6. Has a biological parent or sibling with hypothyroidism.
7. Has history of thyroid disorders such as goiter.

 

 Causes

What are the causes of hypothyroidism?

• The most common cause of hypothyroidism is Hashimoto’s disease, which is an auto-immune disease where the immune system attacks the thyroid.
• There are other causes too. These are:

1. Iodine deficiency in the body.
2. Medications such as lithium, amiodarone and thalidomide.
3. Congenital anomalies such as being born without a thyroid gland.
4. Disorders of the pituitary gland such as non-cancerous growths.
5. Thyroid gland inflammation. Thyroiditis can occur due to viral infections or pregnancy.

 

 Signs & Symptoms

What are the signs and symptoms of hypothyroidism?

• Signs and symptoms that may present include:

1. Fatigue.
2. Elevated levels of cholesterol in the blood.
3. Sensitivity to cold.
4. Numbness in the hands
5. Drooping eyelids.
6. Unintentional and unexplained weight gain.
7. Difficulty concentrating.
8. Depression and anxiety.
9. Frequent or  heavy menses.

 

Types

What are the most common types of hypothyroidism?

• Four forms of hypothyroidism are:

1. Primary hypothyroidism.
2. Secondary hypothyroidism.
3. Tertiary hypothyroidism.
4. Sub-clinical hypothyroidism.

 

Primary hypothyroidism

• It is the most common type of hypothyroidism.
• It causes a direct impact on the thyroid gland.
• The gland produces low levels of thyroid hormones. As a result, more thyroid stimulating hormone (TSH) is produced by the pituitary gland.
• It can be caused by;

1.  Auto-immune diseases such as Hashimoto’s disease.
2.  Radiotherapy.
3.  Surgical operations on the thyroid gland.

 

Secondary hypothyroidism

•  It is a rare form of hypothyroidism.
•  It happens due to underactive pituitary gland.
•  In secondary hypothyroidism, the pituitary gland is prevented from sending thyroid stimulating hormone to the thyroid gland.

 

Tertiary hypothyroidism

• It occurs when the hypothalamus fails to produce adequate amounts of thyrotropin-releasing hormone (TRH).
• The effect of this is that the pituitary gland therefore does not produce adequate TSH amounts.

 

Sub-clinical hypothyroidism

•  Sub-clinical hypothyroidism is also referred to as mild thyroid failure.
•  It occurs due to a slight rise in TSH levels.
• The rest of the thyroid hormones are usually within the normal ranges/ levels.
• It resolves spontaneously in a short period of time.

 

 Diagnostic Procedures  & Tests

How is hypothyroidism diagnosed?

• Patient history-taking and review of symptoms.
• Physical examination. The region around the thyroid is pressed gently to check for swelling.
• Thyroid blood tests. More specifically, thyroid tests are conducted. They are used for measuring the following hormone levels in blood:

1. Thyroid-stimulating hormone (TSH).
2. Triiodothyronine (T3).
3. Tetraiodothyronine (T4).

• Imaging tests of the thyroid, such as:

1.  Thyroid uptake scan.
2.  Computed tomography scan.

 

 Treatment and Management

Hypothyroidism is  a very treatable condition.

How is hypothyroidism treated?

• Hormone replacement therapy. The most common treatment is hormone replacement therapy (HRT).
• Medicines. Levothyroxine is used to replace hormones that the thyroid has failed to produce.

 

 Complications

What are the complications of hypothyroidism?

• Untreated hypothyroidism can lead to development of other medical conditions. These include:

1. Infertility.
2. Miscarriage.
3. Peripheral neuropathy,
4. Myxoedema coma.
5. Heart problems.